This invention relates to a halogen cell, especially to a halogen cell for power storage, electric automobiles and the like.
A positive electrode of a conventional halogen cell may be a porous one comprising carbon felt supported with such a precious metal as palladium. In this halogen cell, halogen gas generated is adsorbed on the positive electrode surface. Since, accordingly, the adsorbed gas substantially decreases the surface area of the positive electrode, the flowing current decreases and a longer charging time is required. Although, at present, electrolyte is forced to permeate the felt-like positive electrode by means of a pump to decrease the volume of the halogen gas adsorbed, it is not satisfactory. At the time of discharge, the quantity of current taken out per unit surface area of the positive electrode is small because the rapid supply of halogen gas dissolved in the electrolyte to the positive electrode surface according to the quantity of discharge is difficult.
On the other hand, a carbon plate may be employed as a negative electrode of a conventional halogen cell. In this halogen cell, hydrogen gas generated is adsorbed on the negative electrode surface at the beginning of discharge. Since, accordingly, the adsorbed gas prevents precipitation of metals and lowers the depositability of the precipitated metals, the quantity of current is limited so as to require a longer charging time. Further, the precipitated metal is liable to be peeled off and a sufficient quantity of charge cannot be obtained.